Code division multiple access (CDMA) communications systems, such as the communications system 100 of FIG. 1, provide wireless communications between a base station 110 and one or more mobile or portable subscriber units, such as a cell phone 130, Personal Digital Assistant (PDA) 140, or Portable Computer (PC) 135 with cellular modem. The base station is typically a computer-controlled set of transceivers that are interconnected to a land-based Public Switched Telephone Network (PSTN) 112 that is connected to a Wide Area Network (WAN) 115, such as the Internet, via a gateway (not shown).
The base station further includes an antenna apparatus 105 for sending forward link radio frequency signals 150a to the mobile subscriber units and for receiving reverse link radio frequency signals 150b transmitted from each mobile subscriber unit. Each mobile subscriber unit also contains an antenna apparatus for the reception of the forward link signals and for the transmission of the reverse link signals. Similar communications techniques are found in Wireless Local Area Networks (WLAN's) 117, where a network router 120 connects wireless access points 125 to the WAN 115. In either the CDMA or WLAN system, multiple mobile subscriber units may transmit and receive signals on the same center frequency, but unique modulation codes distinguish the signals sent to or received from individual subscriber units.
In addition to CDMA, other wireless access techniques employed for communications between a base station and one or more portable or mobile units include those described by the Institute of Electrical and Electronics Engineering (IEEE) 802.11 standard, optionally used in the WLAN 117, and the industry-developed wireless Bluetooth standard. All such wireless communications techniques require the use of an antenna at both the receiving and transmitting site. It is well-known by experts in the field that increasing the antenna gain in any wireless communications system has beneficial effects.
A common antenna for transmitting and receiving signals at a mobile subscriber unit is a monopole antenna (or any other antenna with an omni-directional radiation pattern). A monopole antenna consists of a single wire or antenna element that is coupled to a transceiver within the subscriber unit. Analog or digital information for transmission from the subscriber unit is input to the transceiver where it is modulated onto a carrier signal at a frequency using a modulation code, in the case of the CDMA system, assigned to that subscriber unit. The modulated carrier signal is transmitted from the subscriber unit antenna to the base station. Forward link signals received by the subscriber unit antenna are demodulated by the transceiver and supplied to processing circuitry within the subscriber unit.